It was thus that 15 year old Nakajima Muneyoshi came to the house of Hon'ami Kohõ, a famous sword polisher who was descended from the great family of polisher/appraisers, and was one of the last of the family line. While he studied under Hon'ami, Nakajima had the opportunity to work on many famous blades, including a number from the Imperial collection. One of the highlights for Nakajima during this time was to be allowed to polish the windows in the blades that were currently being made by the Yasukuni Shrine swordsmiths.

Before WWII, Nakajima had often gone to the Yasukuni Shrine on his days off. At first, he just watched. Later, he helped both forge and quench the swords that were being made there. He commented later that he had learned almost as much listening to the swordsmiths talk to his teacher Hon'ami Kohõ. They would discuss the different processes of forging that they had used in making a particular blade. This, coupled with his own observations while opening a window, would prove invaluable to Nakajima's understanding of the different methods of sword forging.

With the outbreak of WWII Nakajima left Japan and went to China. He soon moved to Peking where he set up a shop to make swords. Nakajima had a contract from the Japanese military for three hundred military swords each month. He employed twelve Chinese craftsmen, including two brothers who were swordsmiths. Nakajima said that he and his men had to just about work around the clock to produce the three hundred swords each month. They would work on forging all of the blades and then do the quenching on all three hundred in one night.

On rare occasions Nakajima would totally custom make a complete sword for one of the Japanese military officers. Not only would he forge and quench the blade properly, he would also make a leather covered wooden saya instead of a metal one, and the blade would get a proper polish as well. While in Peking he also had many instances where he would have to do work on old swords as well.